1. Field of the Invention
The present invention relates to a viewfinder display apparatus having a superimpose display function which displays a focus detection region selected from a plurality of focus detection regions set in a viewfinder field.
2. Description of the Related Art
A conventional camera having a superimpose display function which is proposed in Japanese Patent Application Laid-Open No. H01 (1989)-277225 or Japanese Patent Application Laid-Open No. H05 (1993)-333259 is known. In such a conventional camera, a flux of light emitted from an illumination unit arranged in front of a pentaprism is reflected by a quick return mirror constituted by a half mirror through a projection lens to illuminate a plurality of display units arranged on a focusing screen.
In a observing apparatus proposed in Japanese Patent Application Laid-Open No. H04 (1992)-278931, an illumination unit is arranged in a frontal region of a pentaprism to cause illumination light emitted from the illumination unit to transmit through the pentaprism, so that a display body on the focusing screen is irradiated.
In addition, in an optical apparatus proposed in Japanese Patent Application Laid-Open No. H10 (1998)-048733, a focusing point display section corresponding to a focusing point is set in an information display section in a viewfinder which displays a shutter speed and a aperture value.
However, in the camera disclosed in Japanese Patent Application Laid-Open No. H01 (1989)-277225 or Japanese Patent Application Laid-Open No. H05 (1993)-333259, an optical path extending from an illumination unit to a focusing screen is so long that a flux of light from the illumination unit is repeatedly refracted and reflected by a projection lens, a main mirror, or the like many times. Furthermore, since the main mirror is constituted by a half mirror, optical waveguide efficiency is considerably poor.
In addition, in the camera described above, an arrangement space for the projection lens or the like is required, and an adjusting operation for a flux of light emitted from the illumination unit must be performed. For this reason, the camera increases in size and cost to deteriorate the productivity.
On the other hand, when a focal point detection frame is entirely illuminated with LED light, although bright-light shooting can be performed without any problem, a section gleaming with the LED light adversely affects the display in the viewfinder field in photographing in the dark. For this reason, a photographer who looks into the viewfinder may bothersomely see the display in the viewfinder.
In the observing apparatus disclosed in Japanese Patent Application Laid-Open No. H04 (1992)-278931, since light from the illumination unit illuminates a focusing screen through the pentaprism, the optical path becomes short, and optical waveguide efficiency is improved. However, since the illumination unit is arranged in the frontal region of the pentaprism, it is difficult to arrange a built-in flashlight-emitting unit in the frontal region of the pentaprism.
The display body on the focusing screen is constituted by a mirror surface, and does not transmit object light. For this reason, when an observer looks into the viewfinder, a part of an object image corresponding to the display body is blacked out. For example, when the display body on the focusing screen is formed in the shape of two lines, a cross, or the like, the observer is hard to see the object image depending on the shape of the display body.
In the optical apparatus disclosed in Japanese Patent Application Laid-Open No. H10 (1998)-048733, since a focusing point display section corresponding to a focusing point is set in a conventional in-viewfinder information display section which displays a shutter speed and a aperture value outside a viewfinder field, a selected focusing point can be displayed without increasing cost. However, since the position of the focusing point display section is different from an actual focusing point displayed in the viewfinder field, the visibility of the focusing point is not up much.